CN111254800A - A composite beam suitable for urban bridges and its construction method - Google Patents

Abstract

The utility model provides a combination beam suitable for urban bridge, includes the coincide sub-roof beam of multi-disc parallel arrangement, the coincide sub-roof beam includes steel longeron and precast concrete decking, has set firmly the shear force spare on the steel longeron, is equipped with horizontal, vertical and anchor reinforcing bar in the precast decking, and horizontal reinforcing bar and vertical reinforcing bar stretch out to the outside, and the anchor reinforcing bar stretches out to the top, is equipped with vertical cast-in-place seam between the adjacent precast decking, is equipped with the cast-in-place decking of concrete on each precast decking and the vertical cast-in-place seam. The construction method comprises the following steps: manufacturing a steel longitudinal beam and presetting a shear part; erecting a prefabricated bridge deck formwork, laying steel bars in the prefabricated bridge deck, pouring prefabricated bridge deck concrete, demolding and storing to form a superposed sub-beam; transferring and hoisting the superposed sub-beams to be placed on the temporary support; pouring cast-in-place bridge decks and longitudinal cast-in-place seams; and (5) installing a permanent support and dismantling the temporary support. The invention has the advantages of light dead weight, convenient construction, capability of fully exerting the advantages of a combined structure, reasonable stress, strong bearing capacity and the like.

Description

A composite beam suitable for urban bridges and its construction method

technical field

The invention relates to the technical field of bridge engineering, in particular to a composite beam suitable for urban bridges and a construction method thereof.

Background technique

In the construction of urban bridges, more and more attention is paid to the concept of reducing the impact of traffic barriers, focusing on environmental protection, and pursuing project quality and efficiency. Therefore, appropriate structural types and corresponding construction methods are selected to meet the construction concept of "fast, environmentally friendly and efficient". It is the focus and difficulty of urban bridge design.

In recent years, the construction of urban bridges has entered a period of rapid development, and the proportion of prefabricated beams in urban bridges has been increasing. Although the design and construction of traditional prefabricated assembly structures (such as prefabricated small box beams and hollow slabs) are relatively mature, the construction period is long, the tonnage of transportation, erection and installation is large, and the requirements for construction conditions and equipment are high, and the traffic interference is large. The steel plate composite beam is composed of two materials, steel and concrete, which are connected together to form a whole, which gives full play to the tensile performance of steel and the compressive performance of concrete. Good, convenient construction and so on. However, the traditional steel plate composite beam still has a lot of wet work in the field construction, and a lot of formwork is required during construction; the steel structure and the concrete bridge deck are prefabricated separately. During construction, the steel beam is erected first, then the prefabricated bridge deck is installed, and finally the wetted deck is poured. seam. This construction method has the following problems: 1. The steel beam bears most of the dead load, while a small part of the load such as pavement and live load is borne by the composite beam, which does not give full play to the advantages of the composite structure. Further, this stress mode causes the beam height of the steel beam to increase, and the main beam needs to be stiffened vertically and horizontally, which increases the difficulty of construction. When the clear height is limited, it is necessary to raise the line position and increase the project cost; 2. Subject to the hoisting capacity and structural form, the bridge deck is generally prefabricated in longitudinal sections, and there are inevitably horizontal penetration joints, which requires a large amount of on-site work, The quality is not easy to control, and the transverse penetration joints become the weak point of the structure; 3. When the structural system adopts continuous beams, the connecting joints are usually set at the position between the spans where the bending moment is small, and temporary piers need to be set up to complete the connection of steel beams at high altitude. The construction is difficult, the construction precision is low, and the cost of the measures is high.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a composite beam suitable for urban bridges with light weight, convenient construction, full use of composite structure advantages, reasonable stress and strong bearing capacity.

The present invention further provides a construction method of the above-mentioned composite beam suitable for urban bridges.

In order to solve the above-mentioned technical problems, the present invention adopts the following technical solutions:

A composite beam suitable for urban bridges, comprising a plurality of composite sub-beams arranged in parallel in the transverse direction, the composite sub-beams include steel longitudinal beams and concrete prefabricated bridge decks, and shearing members are fixed on the steel longitudinal beams. Protruding to the top of the prefabricated bridge deck, the prefabricated bridge deck is provided with transverse reinforcement bars, longitudinal reinforcement bars and anchor reinforcement bars, the transverse reinforcement bars and longitudinal reinforcement bars protrude to the outside of the prefabricated bridge deck, and the anchor reinforcement bars are extended to the prefabricated bridge deck. Above, a longitudinal cast-in-place concrete joint is arranged between two laterally adjacent prefabricated bridge decks, and each of the prefabricated bridge decks and the longitudinal cast-in-place joint is provided with a concrete cast-in-place deck.

As a further improvement of the above technical solution, a mid-span steel cross beam is fixed between two transversely adjacent steel longitudinal beams. The mid-span steel beam can improve the mechanical properties of the system, and the steel longitudinal beam itself has strong local stability.

As a further improvement of the above technical solution, the thickness of the position where the lower part of the prefabricated bridge deck is in contact with the steel longitudinal beam is greater than the thickness of both sides. The thickness of the position where the lower part of the prefabricated bridge deck is in contact with the steel longitudinal beam is increased to form an inverted trapezoidal section, which is beneficial to improve the mechanical performance of the prefabricated bridge deck itself.

As a further improvement of the above technical solution: it also includes two side fulcrum beams (that is, the beams located at both ends of the bridge), and at least one middle fulcrum beam (usually needs to be set up multiple) between the two side fulcrum beams, so A plurality of the laminated sub-beams are connected between the side fulcrum beam and the middle fulcrum beam close to the side fulcrum beam, and between two adjacent middle fulcrum beams.

As a further improvement of the above technical solution: the side fulcrum beam and the middle fulcrum beam are both cast-in-situ beams, the cast-in-place bridge deck is left with a post-cast section at one end of the middle fulcrum beam, and the upper end of the middle fulcrum beam extends to the post pouring section. Both the side fulcrum beam and the middle fulcrum beam are cast-in-place beams, and there are only longitudinal cast-in-place joints and cast-in-place beams at the top of the pier in the system, which avoids transverse penetration joints in the main stress direction and reduces the weak point and cracking of the structure. Risks and higher structural redundancy; the cast-in-place bridge deck is left with a post-cast section at one end of the beam near the mid-fulcrum point, and the upper end of the corresponding mid-fulcrum cross-beam extends to the post-cast section, so that the cast-in-place mid-fulcrum cross-beam has a T-shaped cross-section. Compared with the conventional rectangular section, it has better mechanical properties and crack resistance, and the structure also has better integrity.

As a further improvement of the above technical solution: the middle fulcrum beam is a high-performance concrete cast-in-place beam. The addition of high-performance concrete can connect the composite sub-beams on both sides as a whole, and the joint position can achieve better mechanical properties than wood, and the connection is more reliable.

As a further improvement of the above technical solution: the side fulcrum beam and the middle fulcrum beam are steel beams, and a plurality of first connecting longitudinal beams are reserved on the inner side of the side fulcrum beam along the length direction. The steel longitudinal beams of the side fulcrum beams are fixedly connected one by one, and a plurality of second connecting longitudinal beams are reserved on both sides of the middle fulcrum beam along the length direction. A corresponding fixed connection. Compared with cast-in-place beams, steel beams are used for side fulcrum beams and middle fulcrum beams, which can eliminate the concrete pouring and maintenance at the position of the middle fulcrum beams. The construction is convenient, the construction period is saved, and the connection is reliable. The overall structure height is small, the line position is reduced, and the engineering cost is saved. It has a wide range of development space for urban viaducts with limited clear height.

A construction method of the above-mentioned composite beam suitable for urban bridges, comprising the following steps:

S1. Make each piece of steel longitudinal beams and preset shear parts on the steel longitudinal beams;

S2. Set up the prefabricated bridge deck formwork, lay the transverse steel bars, longitudinal steel bars and anchoring steel bars in the prefabricated bridge deck, pour the prefabricated bridge deck concrete, demould and store them to form superimposed sub-beams;

S3. Transfer the laminated sub-beam to the bridge position, and hoist each laminated sub-beam and place it on the temporary support on the top of the pier;

S4. Lay the cast-in-place bridge deck and the steel mesh at the longitudinal cast-in-place joints, and pour the cast-in-place bridge deck and the longitudinal cast-in-place joint concrete;

S6. After the concrete strength reaches the design requirements, install the permanent support, remove the temporary support, and complete the system conversion from simply supported to continuous;

S7. Construction of the auxiliary facilities of the bridge deck and completion of the whole bridge construction.

As a further improvement of the above technical solution: when the side fulcrum beam and the middle fulcrum beam are cast-in-place beams, correspondingly, in step S4, after pouring the cast-in-place bridge deck and the longitudinal cast-in-situ joint concrete, bind the side fulcrum beam and the middle fulcrum. Beam reinforcement, and then pour concrete for the side fulcrum beams and the center fulcrum beams.

As a further improvement of the above technical solution: when the side fulcrum beam and the middle fulcrum beam are steel beams, correspondingly, in step S1, the side fulcrum beam and the middle fulcrum beam are made while making each piece of steel longitudinal beam, and in step S3, first Hoist the side fulcrum beam and the middle fulcrum beam, and then hoist each laminated sub-beam, and connect the superimposed sub-beam with the corresponding side fulcrum beam or the middle fulcrum beam to complete the whole bridge erection.

Compared with the prior art, the advantages of the present invention are: the composite beam disclosed in the present invention is suitable for urban bridges, and the transverse bridge adopts a plurality of stacked sub-girders arranged in parallel, and the steel longitudinal beams of the stacked sub-girders are integral with the lower deck deck. Prefabricated and prefabricated bridge decks participate in the force as part of the bridge deck, jointly bear all dead and live loads, and the stress is more reasonable. The beam is connected with the lower prefabricated bridge deck and the upper cast-in-situ bridge deck through shearing parts, and the lower prefabricated bridge deck is connected with the upper cast-in-situ deck by anchoring steel bars, and the bridge deck and the steel longitudinal beam are connected as a whole, which ensures the integrity of the main girder. Connection performance and overall stress performance, this system can give full play to the advantages of steel-concrete composite structure, reduce the beam height of steel longitudinal beams, and reduce the line position, especially suitable for urban bridges with limited clearance under the bridge, which is conducive to saving steel, The overall advantage is obvious in reducing engineering costs; the steel longitudinal beams of the superimposed sub-girders and the lower deck deck are integrally prefabricated, and the upper deck is cast-in-place as a whole. The case of pouring beams), avoiding the transverse penetration joints in the main stress direction, reducing the weak points of the structure and the risk of cracking, the structural performance is more reliable, the durability is good, and the redundancy is higher; the composite sub-beam can be integrated Across prefabrication, transportation, and installation, the longitudinal continuous joints are arranged on the top of the pier, and there is no need to set up temporary piers, which reduces the difficulty of construction and saves the cost of the project; and because the composite sub-beam only includes steel beams and lower prefabricated slabs, it reduces the need for large-sized prefabricated slabs. The difficulty caused by production and transportation, the weight of hoisting is greatly reduced, the difficulty of hoisting construction is reduced, the conventional equipment can be used to the greatest extent, and the investment is saved; There is no need to set the lateral prestress of the bridge deck, the structure is simple, the construction is convenient, and the structural robustness is obviously better than that of the conventional steel plate composite beam with few main beams.

The construction method of the composite beam suitable for urban bridges disclosed by the invention comprises the whole span prefabrication, transportation and installation of the composite sub-beam, the longitudinal continuous joint is arranged on the top of the pier, the temporary pier does not need to be arranged, the construction difficulty is reduced, the project cost is saved, and the lower layer The prefabricated bridge deck acts as a formwork when pouring the cast-in-place bridge deck, which can simplify the construction and reduce the engineering cost.

Description of drawings

FIG. 1 is a schematic structural diagram of a composite beam of the present invention applicable to urban bridges.

FIG. 2 is a schematic diagram of the internal structure of the laminated sub-beam in the present invention.

FIG. 3 is a schematic top view of the composite beam of the present invention applicable to urban bridges.

4 is a schematic structural diagram of a mid-span steel beam in the present invention.

FIG. 5 is a schematic structural diagram of a cast-in-place beam with a fulcrum in Embodiment 1 of the present invention.

6 is a schematic structural diagram of a steel beam in Embodiment 2 of the present invention.

FIG. 7 is a schematic structural diagram of a middle fulcrum steel beam in Embodiment 2 of the present invention.

FIG. 8 is a schematic structural diagram of a steel beam with a side fulcrum in Embodiment 2 of the present invention.

The symbols in the figure indicate: 1, superimposed sub-beam; 11, steel longitudinal beam; 12, prefabricated bridge deck; 13, shearing member; 14, transverse reinforcement; 15, longitudinal reinforcement; 16, anchoring reinforcement; 17, longitudinal cast-in-place 18. Cast-in-place bridge deck; 19. Post-casting section; 2. Side fulcrum beam; 21. First connecting longitudinal beam; 3. Middle fulcrum beam; 31. Second connecting longitudinal beam;

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

Example 1

1 to 5 show the first embodiment of the composite beam suitable for urban bridges according to the present invention. The composite beam suitable for urban bridges in this embodiment includes 6 laminated sub-beams 1, and two adjacent laminated sub-beams The horizontal spacing of 1 is 2.3m. Each laminated sub-beam 1 includes a steel longitudinal beam 11, a prefabricated bridge deck 12, a shearing member 13 (such as a commonly used shearing nail, etc.), an anchoring steel bar 16, and the like. The steel longitudinal beam 11 adopts an I-shaped section, and the beam height is 1100mm, including the steel longitudinal beam top plate, the steel longitudinal beam web plate and the steel longitudinal beam bottom plate. The steel longitudinal beam top plate is 400 mm wide and 16 mm thick; the steel longitudinal beam web plate is 1060 mm high. The thickness is 16mm; the steel longitudinal beam bottom plate is 600mm wide and 24mm thick. The width of the middle beam and the side beams on both sides of the prefabricated bridge deck 12 are 1900mm and 1800mm respectively, and the thickness is 150mm. The included prefabricated slab longitudinal steel bars 15 and prefabricated slab transverse steel bars 14 extend out of the prefabricated bridge deck 12, which is convenient for lap joints. connected as a whole. The transverse bridge direction of the superimposed sub-beam 1 is connected as a whole by the cast-in-place bridge deck 18 and the longitudinal cast-in-place joint 17. The thickness of the cast-in-place bridge deck 18 is 150mm. The panels 12 are connected. The longitudinal cast-in-place joint 17 has a width of 400mm and a thickness of 150mm, and is provided with longitudinal common steel bars, horizontal common steel bars and vertical common steel bars, and is connected with the transverse steel bars 14 of the prefabricated plate. The composite sub-beam 1 is longitudinally provided with two or more cast-in-situ beams, the side fulcrum cast-in-place beam and the middle fulcrum cast-in-place beam are both 1400mm high, and are respectively connected with the composite sub-beam 1 to form a whole.

Further, in this embodiment, in addition to the cast-in-place bridge deck 18 and the longitudinal cast-in-place joint 17, the horizontal connection of each laminated sub-beam 1 also includes a mid-span steel beam 4, and the mid-span steel beam 4 also adopts an I-shaped section, The beam height is 600mm, including the mid-span steel beam web, the mid-span steel beam top plate and the mid-span steel beam bottom plate. Among them, the top plate of the steel beam across the middle and the bottom plate of the steel beam across the middle are both 300mm wide and 16mm thick; the steel beam web is 568mm high and 16mm thick. The steel beams 4 in the middle of the span and the laminated sub-beams 1 are fixedly connected by a plurality of splicing plates and high-strength bolts.

During construction, the steel beam segments are first made, the splicing of each hole steel longitudinal beam 11 is completed in the prefabrication plant, and then the prefabricated bridge deck 12 is completed on the steel longitudinal beam 11. After the concrete strength reaches the design strength, it is demolded and stored to form a laminated sub-beam. 1; then transport the superimposed sub-beam 1 to the bridge position, use the crane to lift and install, after the whole bridge is erected, pour the cast-in-place bridge deck 18 and the longitudinal cast-in-place joint 17, and finally pour the side fulcrum beam 2 and the middle fulcrum beam. 3. Complete the transition from simply supported to continuous system.

The construction method of the composite beam applicable to the urban bridge of the present embodiment is as follows:

1) The steel longitudinal beam top plate, steel longitudinal beam web and steel longitudinal beam bottom plate of steel longitudinal beam 11, the steel longitudinal beam bottom plate, the mid-span steel beam 4 web, the mid-span steel beam top plate and the mid-span steel beam bottom plate, and the For connecting the splicing steel plates of the steel cross beam 4 and each superposed sub-beam 1 in the span, the shear nails are welded on the top plate of the steel longitudinal beam 11 to complete the splicing of the main beam section of each hole and the cross beam section of the mid-span;

2) Set up the prefabricated bridge deck 12 formwork on the prefabricated pedestal of the prefabrication factory, lay the prefabricated slab longitudinal steel bars 15, the prefabricated slab transverse steel bars 14 and the anchoring steel bars 16, pour the prefabricated bridge deck 12 concrete, and demould when the concrete strength reaches more than 90% of the design value , and store it to form a composite sub-beam 1;

3) Transport the laminated sub-beams 1 and the like to the bridge position by the beam transport equipment, and lift and install each laminated sub-beam 1 and the mid-span steel beam 4 on the temporary support;

4) Lay the cast-in-place bridge deck 18 and the longitudinal cast-in-place joint 17 steel meshes, and pour the cast-in-place bridge deck 18 and the longitudinal cast-in-place joint 17 concrete;

5) Bind the side fulcrum beam 2 and the middle fulcrum beam 3 steel bars, and pour the side fulcrum beam 2 and the middle fulcrum beam 3 concrete;

6) After the concrete strength reaches the design strength, install the permanent support, remove the temporary support, and complete the system conversion from simply support to continuous;

7) Construction of bridge deck pavement, railings and other auxiliary facilities to complete the whole bridge construction.

Embodiment 2

6 to 8 show the second embodiment of the composite beam applicable to urban bridges of the present invention. The composite beam applicable to urban bridges in this embodiment is basically the same as the first embodiment, the difference is that the middle fulcrum beam 3 and the side fulcrum beam 2 are made of steel beams. The beam height of the side fulcrum steel beam is 1300mm and the width is 1100mm. The side fulcrum steel beam bottom plate 21 is 1500mm wide and 28mm thick. The top plate of the first connecting longitudinal beam 21 and the top plate of the steel longitudinal beam 11 are connected by welding, the web of the first connecting longitudinal beam 21 and the web plate of the steel longitudinal beam 11 are fixedly connected by splicing steel plates and high-strength bolts, and the bottom plate of the first connecting longitudinal beam 21 is connected to the The webs of the steel longitudinal beams 11 are fixedly connected by splicing steel plates and high-strength bolts; the beam height of the middle fulcrum steel beam is 1300mm and the width is 1500mm, and the bottom plate 23 of the middle fulcrum steel beam is 1900mm wide and 28mm thick. The connecting longitudinal beam 31 is connected with the steel longitudinal beam 11, wherein the top plate of the second connecting longitudinal beam 31 and the top plate of the steel longitudinal beam 11 are connected by welding, and the web of the second connecting longitudinal beam 31 and the web plate of the steel longitudinal beam 11 are connected by splicing steel plates and high-strength steel beams. Bolted connection, the bottom plate of the second connecting longitudinal beam 31 and the web of the steel longitudinal beam 11 are fixedly connected by splicing steel plates and high-strength bolts.

This embodiment is applicable to the construction method of the composite beam of urban bridges as follows:

1) The steel longitudinal beam top plate, steel longitudinal beam web plate and steel longitudinal beam bottom plate of steel longitudinal beam 11 are processed and manufactured by beam section, side fulcrum steel beam, middle fulcrum steel beam, span middle steel beam 4 web, span middle steel beam The top plate and the bottom plate of the steel beam in the middle span, as well as the spliced steel plates used to connect the steel beam 4 in the middle span and each superposed sub-beam 1, weld shear nails on the top plate of the steel longitudinal beam 11 to complete the main beam section of each hole and the middle span. Splicing of beam sections;

2) Set up the prefabricated bridge deck 12 formwork on the prefabricated pedestal of the prefabrication factory, lay the prefabricated slab longitudinal steel bars 15, the prefabricated slab transverse steel bars 14 and the anchoring steel bars 16, pour the prefabricated bridge deck 12 concrete, and demould when the concrete strength reaches more than 90% of the design value , and store it to form a composite sub-beam 1;

3) Transport the laminated sub-beams 1 and the like to the bridge position through the beam transport equipment, first hoist the side fulcrum steel beam 13 and the middle fulcrum steel beam 14, and then hoist and install each laminated sub-beam 1 and the mid-span steel beam 4 on the temporary support. On the seat, then through the upper first connecting longitudinal beam 21 reserved by the side fulcrum steel beam, the top plate of the second connecting longitudinal beam 31 reserved by the middle fulcrum steel beam is welded with the top plate of the steel longitudinal beam 11, and the first connecting longitudinal beam 21 , The web and bottom plate of the second connecting longitudinal beam 31 are bolted to the web and bottom plate of the steel longitudinal beam 11 to complete the erection of the full bridge;

4) Lay the cast-in-place bridge deck 18 and the longitudinal cast-in-place joint 17 steel meshes, and pour the cast-in-place bridge deck 18 and the longitudinal cast-in-place joint 17 concrete;

5) After the concrete strength reaches the design strength, install the permanent support, remove the temporary support, and complete the system conversion from simply support to continuous;

6) Construction of bridge deck pavement, railings and other auxiliary facilities to complete the whole bridge construction.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art, without departing from the scope of the technical solution of the present invention, can make many possible changes and modifications to the technical solution of the present invention by using the technical content disclosed above, or modify it into an equivalent implementation of equivalent changes. example. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solutions of the present invention should fall within the protection scope of the technical solutions of the present invention.

Claims (10)

1. The utility model provides a composite beam suitable for city bridge which characterized in that: the composite bridge deck slab comprises a plurality of composite sub-beams (1) which are arranged in parallel in the transverse direction, wherein each composite sub-beam (1) comprises a steel longitudinal beam (11) and a concrete prefabricated bridge deck (12), a shear part (13) is fixedly arranged on each steel longitudinal beam (11) and extends out of the upper side of each prefabricated bridge deck (12), transverse reinforcing steel bars (14), longitudinal reinforcing steel bars (15) and anchoring reinforcing steel bars (16) are arranged in each prefabricated bridge deck (12), each transverse reinforcing steel bar (14) and each longitudinal reinforcing steel bar (15) extend out of the outer side of each prefabricated bridge deck (12), each anchoring reinforcing steel bar (16) extends out of the upper side of each prefabricated bridge deck (12), a concrete longitudinal cast-in-place seam (17) is arranged between every two transversely adjacent prefabricated bridge decks (12), and cast-in-place concrete bridge decks (18) are arranged on each prefabricated bridge deck (12) and each longitudinal.

2. The composite beam suitable for urban bridges of claim 1, wherein: a midspan steel cross beam (4) is fixedly arranged between two transversely adjacent steel longitudinal beams (11).

3. The composite beam suitable for urban bridges of claim 1, wherein: the thickness of the lower part of the prefabricated bridge deck (12) in contact with the steel longitudinal beam (11) is larger than that of the two sides.

4. The composite beam suitable for urban bridges of any one of claims 1 to 3, wherein: the folding device is characterized by further comprising two side fulcrum beams (2), at least one middle fulcrum beam (3) is arranged between the two side fulcrum beams (2), and a plurality of folding sub-beams (1) are connected between the side fulcrum beams (2) and the middle fulcrum beams (3) close to the side fulcrum beams (2) and between the adjacent two middle fulcrum beams (3).

5. The composite beam suitable for urban bridges of claim 4, wherein: the side fulcrum beam (2) and the middle fulcrum beam (3) are both cast-in-place beams, a post-cast section (19) is reserved at one end, close to the middle fulcrum beam (3), of the cast-in-place bridge deck (18), and the upper end of the middle fulcrum beam (3) extends to the post-cast section (19).

6. The composite beam suitable for urban bridges of claim 5, wherein: the middle fulcrum beam (3) is a high-performance concrete cast-in-place beam.

7. The composite beam suitable for urban bridges of claim 4, wherein: the steel beam is characterized in that the edge fulcrum beam (2) and the middle fulcrum beam (3) are steel beams, a plurality of first connecting longitudinal beams (21) are reserved on the inner side of the edge fulcrum beam (2) along the length direction, the first connecting longitudinal beams (21) are fixedly connected with the steel longitudinal beams (11) close to the edge fulcrum beam (2) in a one-to-one correspondence mode, a plurality of second connecting longitudinal beams (31) are reserved on the two sides of the middle fulcrum beam (3) along the length direction, and the second connecting longitudinal beams (31) are fixedly connected with the steel longitudinal beams (11) close to the middle fulcrum beam (3) in a one-to-one correspondence mode.

8. The construction method of a composite girder applicable to an urban bridge according to any one of claims 1 to 7, wherein: the method comprises the following steps:

s1, manufacturing each steel longitudinal beam (11) and presetting a shearing force piece (13) on each steel longitudinal beam (11);

s2, erecting a prefabricated bridge deck (12) template, laying transverse steel bars (14), longitudinal steel bars (15) and anchoring steel bars (16) in the prefabricated bridge deck (12), pouring concrete of the prefabricated bridge deck (12), demolding and storing to form a superposed sub-beam (1);

s3, transferring the superposed sub-beams (1) to a bridge site, and hoisting each superposed sub-beam (1) to be placed on the pier top temporary support;

s4, laying a cast-in-situ bridge deck (18) and a reinforcing mesh at the longitudinal cast-in-situ seam (17), and pouring concrete of the cast-in-situ bridge deck (18) and the longitudinal cast-in-situ seam (17);

s6, after the concrete strength meets the design requirement, installing a permanent support, and removing a temporary support to complete the system conversion from simple support to continuous support;

and S7, constructing auxiliary facilities of the bridge floor to finish full-bridge construction.

9. The construction method of the composite girder applicable to urban bridges according to claim 8, wherein: in the step S4, after concrete of the cast-in-place bridge deck (18) and the longitudinal cast-in-place seam (17) is poured, reinforcing steel bars of the side fulcrum beam (2) and the middle fulcrum beam (3) are bound, and then concrete of the side fulcrum beam (2) and the middle fulcrum beam (3) is poured.

10. The construction method of the composite girder applicable to urban bridges according to claim 8, wherein: in the step S1, the side fulcrum beam (2) and the middle fulcrum beam (3) are manufactured while the steel longitudinal beams (11) are manufactured, in the step S3, the side fulcrum beam (2) and the middle fulcrum beam (3) are hoisted firstly, then the superposed sub-beams (1) are hoisted, the superposed sub-beams (1) are fixedly connected with the corresponding side fulcrum beam (2) or middle fulcrum beam (3), and full-bridge erection is completed.

Images